======= Mounting VPS image offline =======
first use fdisk to see partitions' offsets 
<code bash>
# fdisk -l /dev/xvda

Disk /dev/sda: 149.1 GiB, 160041885696 bytes, 312581808 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x000c25fa

Device     Boot    Start       End   Sectors   Size Id Type
/dev/sda1  *        2048  19531775  19529728   9.3G 83 Linux
/dev/sda2       19531776  58593279  39061504  18.6G 83 Linux
/dev/sda3       58595326 312580095 253984770 121.1G  5 Extended
/dev/sda5       58595328 312580095 253984768 121.1G 83 Linux

</code>
or you can use it for an image, here is another example with usb flash.iso file
<code bash>
# fdisk -l vps01.iso

Disk finexo-flash.iso: 7.2 GiB, 7747397632 bytes, 15131636 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: EEADAEAD-CA33-4934-81D5-06161B87C41C

Device               Start      End  Sectors  Size Type
vps01.iso1     2048 12994559 12992512  6.2G Linux filesystem
vps01.iso2 12998656 15131602  2132947    1G EFI System

</code>

The offset of the first partition is in both cases 2048 *sectors* not bytes. One sector is 512 Bytes so the real offset in bytes is 2048*512 (2^11*2^9 = 2^20 = 1048576)
  mount -o loop,offset=$[2048*512]  vps01.iso /mnt
  
...well done :-)